Ground Control best spring rate?


JDMDingo

JDMDingo

Spoon whore
Joined
Feb 26, 2011
Messages
310
I have the Spoon springs and I hate the wheel gap on my car, I have been thinking about switching to Ground Control on my stock struts. I do not intend on slamming my EK, just get rid of the wheel gap maybe 3 - 4cm.

What spring rate would be good for Ground Control + Stock Struts? It's a daily driver with week-end spirited driving around some mountain corners.

Thanks for the help
 
stock shocks will really limit you from getting anything stiff enough for a 4cm drop in my opinion. Stock will suffice but your car might be bouncy and your shock life will be reduced. if the shocks are already old it worsens the problem.
 
My 2000 USDM EK has Skunk2 lowering sleeves on stock struts for 12 years now and still feels great, granted I have lived in Japan for 6 of that. I will probably upgrade to koni yellows in the future, I leave my current job in 6 months and start a new on. If I get the job I am looking at I get a nice set of full coilovers.
 
JDMDingo said:
I will probably upgrade to koni yellows in the future, I leave my current job in 6 months and start a new on. If I get the job I am looking at I get a nice set of full coilovers.
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Koni/GC is better than most setups you can buy under £1k. IF you've got them, I wouldn't bother with 'full coilovers', they'll offer nothing over Koni/GC bar a load of anodised crap you don't need combined with worse damping and bad aftersales service.
 
Kozy said:
Koni/GC is better than most setups you can buy under £1k. IF you've got them, I wouldn't bother with 'full coilovers', they'll offer nothing over Koni/GC bar a load of anodised crap you don't need combined with worse damping and bad aftersales service.
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so then which spring rate with koni yellows?
 
Thanks to the adjustment they can work with anything up to 500lbs. I wouldn't recommend going below 250 with them though, I did and they become a bit harsh.

With a 40mm drop, I'd say 350-400lbs would be about right.
 
Kozy said:
Thanks to the adjustment they can work with anything up to 500lbs. I wouldn't recommend going below 250 with them though, I did and they become a bit harsh.

With a 40mm drop, I'd say 350-400lbs would be about right.
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As all ways.....thanks
 
Kozy said:
Thanks to the adjustment they can work with anything up to 500lbs. I wouldn't recommend going below 250 with them though, I did and they become a bit harsh.

With a 40mm drop, I'd say 350-400lbs would be about right.
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So I'm finally ordering ground controls a koni yellows on Monday. There is a complete setup with top hat special $1049.00, these are the available spring rates.

Front: 340, 380 or 430
Rear: 250, 350 or 430

Its a daily driver with mountain road and autocross about 1 or 2 times a month. Our roads are fairly smooth, I have a wife and 2 year old.
 
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Well your Spoons are 350/310 which is quite high for lowering springs (especially ones that don't lower much) so the 380/350 combo will probably work pretty well for you.

Bear in mind that it is the rear spring rate which has the biggest impact on ride comfort, but obviously the trade of with a lower rate is more understeer.

This is going on an EK9 right?
 
Yeah, ek9.....I have so much oversteer with the spoon springs. Stock I never had a problem, just very slight under steer, after fitting the spoon springs the car feels so back rear end light its scary. I have spun out twice and a few scares. Once tapping a mountain! That was on month old Advan AD08 tyres. I will be corner balancing the car once I get the GC/konis fitted. Thanks for the help, I will be skypping Ground Control tomorrow.
 
Just got off the phone with Trevor at Ground Control, he highly suggested I go with 380 front and 300 rear....he is not charging extra for the custom rates and giving me the Honda-tech discount price of $1049.00 USD, great customer service.
 
JDMDingo said:
Yeah, ek9.....I have so much oversteer with the spoon springs. Stock I never had a problem, just very slight under steer, after fitting the spoon springs the car feels so back rear end light its scary. I have spun out twice and a few scares.
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Ah you must be Oki-Ek9 on HT then...

Can't say I ever had that problem, and I also had a 24mm rear ARB, lots more front camber than rear, polybushed RTAs and huge front brake bias to all exacerbate the problem.

I guess I prefer my cars to handle quite 'loose'. :shocked:
 
Hi Kozy, I'm back to ask more questions.

I asked someone a few weeks back about this Koni/Eibach with Ground control setup as I'd never heard of it and EK4 Luke off here kindly got back to me with some links for all three. They do work out a fair bit more than say Meister R's at around £900GBP + VAT but you think that they are definitely worth paying that bit more as they're better than coilovers?

Here's the link to that page here.

http://www.ek9.org/forum/suspension/57425-best-coilovers-lows.html

Just one other thing RE Spring rates. The OP of this thread discussed them based on a 40mm drop. I'd probably be going nearer 50-60mm drop in my EK9 if I went for this setup, would I be back to having a bumpy car with it bottoming out again over flat surfaces like I have with my current Daiyamas if I was to go as low as 60mm, also what would be the best spring rate setup on the Koni Yellows with Eibachs do you think?

Again it'd be a daily driver, (8 miles usage a day) weekdays and some spirited driving on the weekends on A and B roads.

Thanks.


Marc
 
Well a quick way to check if your spring rates are right for the ride height is to have a guess at the damper stroke and the force required to compress it.

Assume the stock EK9 has 6" of bump travel at the wheel. Through a .7 motion ratio that's 4.2" at the damper. The standard rates at 250lbs/in, so 4.2 x 250 = 1050lbs to compress the suspension fully.

Now, you want to drop the car 2", so that reduces to 4" wheel travel and 2.8" damper stroke. You now need to resist 1050lbs with 2.8" of travel, so that's 1050/2.8 = 375lbs/in.

Now, I've only guessed those lengths, but that's how I would be working it out, I'd also add on some additional rate for safety depending on how well everything was measured. With guesses like these I would say 20% which would take it to 450bs/in or 8kg/mm. That's knocking around the top of the range that off the shelf Konis can handle. You'll not be able to play with the adjustments much at that level.

As for whether the Koni/GC combo is worth it, the short answer is 'It depends'.

Coilovers will be cheaper. They'll also offer more adjustability, especially if you want to go low as you can do this without affecting the damper stroke. They're also mono-tube, if that matters.

A damper is not better-by-default because it is mono-tube, and the Konis are very very good twin-tubes, I'd wager that if you put a set of Konis on a dyno vs a set of Bor-Chuann manufactured dampers, the Konis would easily outperform the Taiwanese gear.

It doesn't make the Taiwanese dampers bad, they have a huge following which suggests they do a good enough job for the majority, but it's just that they'll never be quite as good. The Konis will be better matched per set, the adjustments will be more repeatable, and the endurance/performance should be more predictable.

The springs will be better too. People think a spring is a spring is a spring, but again it's the tolerances that they are manufactured to which decides the performance. Low quality springs might have rate variations of 5-10% from stated, coupled with a similar 5-10% variation in damper performance per side, you could end up with a 20% mismatch between spring and damper across an axle. It's this sort of thing that companies like Koni and Eibach (GC's springs) do that bit better, and what makes them the default choice in the US.

I think of it like steak, 14oz Rump vs 10z ribeye. Some people want the quantity, some want the quality. Neither is the wrong choice, you just pick which works best for you.

All this said, at -60mm, you're not going to have much ride quality left and the handling will be heavily compromised, so pretty much anything will do.
 
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Bloody hell, that's one hell of a response mate fair played!!

It's good to get an understanding of how things work. I was having a read through your suspension sticky the other week however maths is not my strong point lol!

Do you work for a Motorsport team as you studied in that field didn't you?

I checked the Koni's with GC kit and they're actually cheaper this week than what they were 2 weeks ago. They're working out around £736 inc VAT and delivery from the States, they were nearer £900 a few weeks ago.

TBH I will probably go for that kit eventually instead of the coilovers and go for a 50mm drop, think I'd be happy with that and it wouldn't compromise the road comfort either and would be a vast improvement over what's on the car at present.

My Daiyama's are horrendous at the moment. Next time it's in the garage I'm going to ask my mechanic to increase the road height a tad and see if it helps with the handling till I get some better suspension.

Thanks again for your input and help.

Cheers.
 
Yes try and raise the ride height and it might improve a bit, running low is not really good for anything but looks unless it's a pure race/track car. If aiming for the best handling on the road, I would be keeping within about 15-20mm of standard really.

I don't work for a motorsport team. I'd like to, but the money generally sucks in motorsport (you do it for the love of it) and there is no motorsport industry on the Isle of Wight anyway.
 
Kozy said:
Yes try and raise the ride height and it might improve a bit, running low is not really good for anything but looks unless it's a pure race/track car. If aiming for the best handling on the road, I would be keeping within about 15-20mm of standard really.

I don't work for a motorsport team. I'd like to, but the money generally sucks in motorsport (you do it for the love of it) and there is no motorsport industry on the Isle of Wight anyway.
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Definitely, I will get it raised to around a 30mm drop it should help it no end. It's just too crashy at the moment it's actually rattling my chest and ribs when I go over a bump it's that painful.

Even on smooth roads it's bouncy and that isn't good or right. Getting too old to have my chest rattled everywhere I go!

Shame you can't work in the career you love because the money is so poor. I think you'd need to be involved in one of the major works teams to be on good cash whether that's in racing or rallying.

I know a lad that worked with Mitsubishi Ralliart before they pulled out of the WRC, he now works for M Sport Ford in Cumbria as an engineer, gets to go all over the world with the rally team he's very lucky.

He was always a decent mechanic and I think his dad had contacts in the Motorsport community which helped but still, living the dream or what!

Thanks again mate.

Cheers.
 
Edgar friendly said:
Definitely, I will get it raised to around a 30mm drop it should help it no end. It's just too crashy at the moment it's actually rattling my chest and ribs when I go over a bump it's that painful.

Even on smooth roads it's bouncy and that isn't good or right. Getting too old to have my chest rattled everywhere I go!
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That could be the damping as much as the ride height and spring rate. Do you know what rate the current springs are? -30mm sounds good though.

Edgar friendly said:
Shame you can't work in the career you love because the money is so poor. I think you'd need to be involved in one of the major works teams to be on good cash whether that's in racing or rallying.

I know a lad that worked with Mitsubishi Ralliart before they pulled out of the WRC, he now works for M Sport Ford in Cumbria as an engineer, gets to go all over the world with the rally team he's very lucky.

He was always a decent mechanic and I think his dad had contacts in the Motorsport community which helped but still, living the dream or what!
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Yea right, sounds good! I know a couple of my classmates are currently working on the pitlane in LMP and F1, but they were grafters through and through, without any real ties so the jet set, hard graft life is good for them and the income was almost secondary. Me, as a desk jockey with a family, I need the home base and decent income which does change the prospects somewhat!

If you do go ahead and change your setup, come back and let us know if you like it! :))
 
Kozy said:
That could be the damping as much as the ride height and spring rate. Do you know what rate the current springs are? -30mm sounds good though.



Yea right, sounds good! I know a couple of my classmates are currently working on the pitlane in LMP and F1, but they were grafters through and through, without any real ties so the jet set, hard graft life is good for them and the income was almost secondary. Me, as a desk jockey with a family, I need the home base and decent income which does change the prospects somewhat!

If you do go ahead and change your setup, come back and let us know if you like it! :))
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I haven't got a clue what the rates are tbh mate. All I know is that when I got it I'd asked Daz to lower it as he sent me a pic of the car and it was sitting way too high so I asked him to decrease the height and it's pretty much slammed now especially at the front.

I don't know how the damping is adjusted on mine. Daz says they are Zeals but a previous owner says they're Daiyamas. Zeals supposedly have 6 different settings for damping which you adjust at the top of the damper/strut but I don't know how it works with the ones that are on.

Can I adjust the spring rates on coilovers or would they need to be sent off for a specialist to do that?
 
You can swap the springs, they're usually pretty cheap. It means taking the entire damper unit off the car and dismantling them though.

Thing is you'll have to raise the ride height if you lower the spring rate as it will bottom out otherwise.
 
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